Both sides previous revision
Previous revision
Next revision
|
Previous revision
Next revision
Both sides next revision
|
electrical:12v:b2b [2021/06/05 18:59] frater_secessus [Renogy] |
electrical:12v:b2b [2021/06/18 18:57] frater_secessus [gotchas] |
- enough //time// at that voltage for the battery to stop accepting much current.(([[electrical:12v:battery_capacity|C/100]] to C/200)) If you aren't //driving// for (say) [[opinion:frater_secessus:charging_faster|5 hours]] then the charger can't //charge// for 5 hours to meet the battery's needs. ((DC-DC chargers were first marketed for cruisers (powered boats) since they run the engines ("cruise") for hours each day.)) This is where [[electrical:12v:alt_and_solar|a bit of solar helps with the long-duration duties]]. | - enough //time// at that voltage for the battery to stop accepting much current.(([[electrical:12v:battery_capacity|C/100]] to C/200)) If you aren't //driving// for (say) [[opinion:frater_secessus:charging_faster|5 hours]] then the charger can't //charge// for 5 hours to meet the battery's needs. ((DC-DC chargers were first marketed for cruisers (powered boats) since they run the engines ("cruise") for hours each day.)) This is where [[electrical:12v:alt_and_solar|a bit of solar helps with the long-duration duties]]. |
| |
DC-DC chargers are often triggered by the IGN circuit, but [[electrical:12v:voltage_sensing_delay|voltage sensing can be added]]. | DC-DC chargers are often triggered by the IGN circuit, but [[electrical:12v:voltage_sensing_delay|voltage sensing can be added]] to that circuit. Others are triggered by chassis-side voltage alone. |
| |
Dual-input (alternator + solar) units make charging source decisions that are sometimes quirky. See below. | Dual-input (alternator + solar) units make charging source decisions that are sometimes quirky. See below. |
===== examples - with MPPT ===== | ===== examples - with MPPT ===== |
| |
Combining the [[electrical:solar:charge_controller|solar charge controller]] and DC-DC charger in one unit can have benefits in cleaner/simpler installation and perhaps cost over separate components. The downsides are less configurabilty((you aren't choosing your own highly-configurable components)), single points of failure, and limited options on solar input. | Combining the [[electrical:solar:charge_controller|solar charge controller]] and DC-DC charger in one unit can have benefits in cleaner/simpler installation, starter battery maintenance from solar, and perhaps cost over separate components. The downsides are less configurabilty((you aren't choosing your own highly-configurable components)), single points of failure, and limited options on solar input. |
| |
Combo units typically have much **lower maximum panel input voltages** (as low as 23v) than a standalone charge controller would (60v - 150v). This limits the solar configuration in a few ways: | Combo units typically have much **lower maximum panel input voltages** (as low as 23v) than a standalone charge controller would (60v - 150v). This limits the solar configuration in a few ways: |
* driving in daytime: 25A alternator + 15A solar = 40A total charging | * driving in daytime: 25A alternator + 15A solar = 40A total charging |
| |
[[https://www.renogy.com/content/RBC3050D1S-G1/RBC3050D1S-Manual.pdf|Behavior is the same for the 30A model]] (pdf) only 15A + 15A where the 50A model was 25A + 25A above. | [[https://www.renogy.com/content/RBC3050D1S-G1/RBC3050D1S-Manual.pdf|Behavior is the same for the 30A model]] (pdf) except 15A + 15A //vs// 25A + 25A above. |
| |
| |
| |
[[http://www.bogartengineering.com/products/solar-charger.html|Bogart's SC-2030]] can work as a DC-DC charger as well as a PWM charge controller. | [[http://www.bogartengineering.com/products/solar-charger.html|Bogart's SC-2030]] can work as a DC-DC charger as well as a PWM charge controller. |
| |
| ===== gotchas ===== |
| |
| Observe voltage input maximums on units with built-in solar charge controllers. |
| |
| Voltage-sensing units((triggered by elevated chassis voltage)) can misbehave when an undersized starter battery charger/maintainer is attached. For this example we assume a 10A maintainer and a 20A DC-DC charger. |
| |
| - starter battery voltage rises from 10A maintainer charging... |
| - triggering the DC-DC charger... |
| - which begins pulling up to 20A from the chassis |
| - pulling down the starter battery since the 10A maintainer cannot keep up |
| - starter battery voltage drops far enough the DC-DC turns off |
| - repeat forever |
| |
| The workaround is to either charge the house battery first or to buy a big enough starter battery maintainer to support both the starter battery and DC-DC charger loads. |
| |
===== further reading ===== | ===== further reading ===== |
| |
[[https://diysolarforum.com/threads/dc-dc-charger-b2b-options-and-general-discussion.17211/|DC-DC charger (B2B) options and general discussion]] on DIY Solar Power Forum. | [[https://diysolarforum.com/threads/dc-dc-charger-b2b-options-and-general-discussion.17211/|DC-DC charger (B2B) options and general discussion]] on DIY Solar Power Forum. |